To spectate means to watch a sports event or a game rather than play in it. It is a slightly odd word, and it is worth knowing why. English already has 'watch', which does the job perfectly well, so 'spectate' gets used when the speaker wants to stress the ROLE — you are there as an audience member, not a player. 'I hurt my knee, so I'll just spectate today.' A key grammar point: 'spectate' normally takes no object. You say 'I spectated' or 'I went to spectate', not 'I spectated the match'. If you have an object, use 'watch': 'I watched the match.' Native speakers feel this quite strongly, and 'spectate the game' sounds wrong to most of them. Where do you meet it? Mostly around amateur sport, e-sports, cycling races, running events — organisers write things like 'Free to spectate' or 'best places to spectate the race'. In gaming it has a specific life: in online games, spectate mode lets you watch other players. That use is now very common among young people. It is not a formal word and not a common one; in ordinary conversation people just say 'watch'.

觀看(比賽)、當觀眾。電玩裡的「觀戰模式」就是 spectate mode。日常說「看比賽」用 watch 就好,spectate 強調的是「以觀眾身分在場」。